I of course saved Greg's email as I treasure his pearls of wisdom. Here is the scaup discussion:
Sara Zagorski
Wethersfield
Sent from my iPhone
Begin forwarded message:
> From: greg hanisek via CTBirds <ctbirds at lists.ctbirding.org>
> Date: November 30, 2016 at 3:32:46 PM EST
> To: CT Birds <ctbirds at lists.ctbirding.org>
> Subject: [CT Birds] scaup vs scaup
> Reply-To: greg hanisek <ctgregh at yahoo.com>
>> I spent an enjoyable 20 min+ this morning studying a mixed flock of 6 scaup on mirror flat Lake Waramaug in New Preston. The birds were at close range (good views with bins; very detailed views with scope). Since this is a well-known ID trouble-spot I thought it would be worth explaining my methods (which have been sharpened considerably by spending time with eBird reviewer Ian Worley of Cornwall, VT, for hours in winter 2015-16 under the Champlain Bridge on the VT side of L Champlain). This spot can hold many hundreds to several thousand of both scaup, each in significant numbers. Ian is a real stickler for accurate counts and/or good ratios. Trying to produce both with bitter winds whipping across the lake and churning the surface can turn production of a reasonable eBird checklist into a humbling experience. But it does teach how variable the shapes of these bids can be when not swimming on a placid surface.
> Waramaug was "Lake Placid" this morning, but it still took some patient watching to see each bird in a position that allowed for a confident species ID. When working on these birds here are 4 things to look for (none was an adult male) 1/ overall size comparison; 2/ bill size comparison; 3/ head shape of bird in profile with erect posture 4/ head shape when seen from directly behind. (A stretched wing will of course clinch things).
> 1/ When seen side-by-side, the Lesser will look smaller and especially less bulky than the Greater; 2/ Again side-by-side, the Lesser's bill will look smaller and less formidable than the Greater's; 3/ In a good profile view the Lesser's head will show a small but obvious knob or knot at the rear crown, so the high spot on the head is behind the eye; Greater will show a more evenly sloping crown (the high spot may not be obvious but it will be above or in front of the eye; 4/ Try to observe the back of the head, being patient enough to get a view from directly behind if possible. In this view the head pinches in a bit at the eyes; you want to look at the area above this "pinch" - in Lesser this area is higher and narrower; in Greater it's lower and wider.
> BUT ALWAYS NOTE HOW MUCH HEAD SHAPE CAN CHANGE WHEN THE BIRDS ARE ACTIVE OR HAVE HEADS TUCKED. However, sometimes the Lesser's "knot" really sticks out on a tucked head.
> Greg HanisekWaterbury
> _______________________________________________
> This list is provided by the Connecticut Ornithological Association (COA) for the discussion of birds and birding in Connecticut.
> For subscription information visit http://lists.ctbirding.org/mailman/listinfo/ctbirds_lists.ctbirding.org